1. Field of the Invention
The present invention relates to a resource control method in a mobile communication system between a base station and a plurality of mobile stations, the base station, the mobile stations and a mobile communication system including the base station and the mobile stations.
2. Related Background Art
In mobile communication environments, variations in a receiving level and an amount of interference are extremely depending on the movement of terminals and the changes of radio wave environments, and variations in an amount of resources such as a radio channel necessary for a communication are large. In a cellular system, an amount of resources available for each cell varies, and, by a handover due to the movement of the terminal, the resource that can be used by terminals changes as time passes. Accordingly, it is difficult to absolutely guarantee so-called QoS (a quality of service for a network) such as an error rate and a transmission speed all over the time of communications, which is allocated when the terminal originates a new connection request and handover request.
In a conventional quality guarantee service, e.g., in a circuit-switched voice service in the mobile communication, when initially required QoS becomes unfulfilled because of a decrease in a receiving level and an increase in interference during the communication and because of inexistence of a non-busy channel in a handover destination when a handover is performed, in other words, when it is impossible to keep voice QoS a certain predetermined level, the communication has been stopped at that time. For users, the cut-off of the communication desired to be continued is a large loss in a service.
On the other hand, in the invention titled as “A Slot Allocation Method in Mobile Communication, Base Station using the Method, and Mobile Stations using the Method”, which is disclosed in Japanese Patent Laid-Open No. 2001-177865, each user notifies to a network a QoS request in which two values composed of the maximum and minimum of resources required are included. When a new connection request is originated, the network checks allocatable resources, and the resources are utilized within the range between an amount of the maximum requested resources and an amount of the minimum requested resources of the connection request.
However, in this method the resources are allocated depending on a traffic state at the time when a new connection request or a handover request is originated. Accordingly, when a plurality of service classes exist, if the times of issuing connection requests by a plurality of users of the same service class are different from each other, unfairness may occur among users of the same service class. Specifically, the unfairness occurs if the maximum request resources are allocated to the user issuing the request in non-congested condition and the minimum request resources are allocated to the user issuing the request in congested condition.
Among the users of different service classes, the users of a low priority service class who originate the request in non-congested condition, are sometimes allocated with the maximum request resource amount, and the users of a high priority service class who originate the request in congested condition, are sometimes allocated with the minimum request resource amount. Accordingly, unfairness occurs for these users of the different service classes. Existence of the unfairness among the users of the same service class and different service classes makes it impossible to provide service with fairness, and may deteriorate a degree of satisfaction of users.
For example, as shown in FIGS. 7A to 7D, mobile stations (hereinafter referred to as MS) MS1 and MS3 shall belong to a high service class demanding a high transmission rate, and a MS2 shall belong to a low service class demanding a low transmission rate. Note that FIG. 7A shows a communication from a base station to each mobile station and FIG. 7C shows a communication from the mobile station to the base station.
The thickness of the arrow in FIG. 7A indicates a magnitude of transmission power allocated to each MS, and a stacking graph of the transmission power allocated to each MS is shown in FIG. 7B. The thickness of the arrow in FIG. 8A described later similarly shows a magnitude of transmission power, and FIG. 8B described later similarly shows a stacking graph of the transmission power. Moreover, the thickness of the arrow in FIG. 7C indicates a magnitude of received power relating to a received signal from each MS, and a stacking graph of the received power from each MS is shown in FIG. 7D. The thickness of the arrow in FIG. 8C described later similarly shows the magnitude of the received power, and FIG. 8D described later shows the stacking graph of the received power similarly.
As shown in FIGS. 7A to 7D, when the MS1 and MS2 originated a new connection request, there was a margin of resources. Accordingly, the resources were allocated to the MS1 and MS2 for the maximum request of QoS. For example, the resources were allocated to the MS1 and MS2 so that transmission rates of 384 kbps and 192 kbps could be realized.
However, when the MS3 originates a new connection request in this state, the remaining transmission power resource is small. Accordingly, the transmission rate as little as 64 kbps can be provided to the MS3. Therefore, unfairness occurs in the service provided to the MS1 and MS3 that are users of the same service class. 64 kbps is allocated to the MS3 of a high service class and 192 kbps is allocated to the MS2 of a low service class. Thus, unfairness occurs also in the service provided to the MS2 and MS3 that are users of the different service classes.
Such a state may occur also when the handover request is originated. Specifically, as shown in FIGS. 8A to 8D, since there was a margin of the resources when the MS1 and MS2 originated the handover request, the resources were allocated to the MS1 and MS2 for the maximum request of QoS. For example, the resources were respectively allocated to the MS1 and MS2 so that the transmission rates of 384 kbps and 384 kbps could be realized.
However, when the MS3 originates the handover request in this state, the remaining transmission power resource is small. Accordingly, the transmission rate as little as 32 kbps can be provided to the MS3. Therefore, unfairness occurs in the service provided to the MS1 and MS3 that are the users of the same service class. 32 kbps is allocated to the MS3 of the high service class, and 384 kbps is allocated to the MS2 of the low service class. Thus, unfairness occurs also in the service provided to the MS2 and the MS3 that are the users of the different service classes.
As described above, services cannot be provided with fairness by the conventional method, and the conventional method may deteriorate a degree of satisfaction of users.
In the foregoing conventional resource control method, the maximum request resource is allocated to the user issuing the new connection request or the handover request in non-congested condition, and the minimum request resource is allocated to the user issuing the new connection request or the handover request in congested condition. In such a case, unfairness occurs in the service among the users of the same service class.
Furthermore, the maximum request resource is allocated to the user of the low priority class issuing the new connection request or the handover request in non-congested condition, and the minimum request resource is allocated to the user of the high priority class issuing the new connection request or the handover request in congested condition. In such a case, unfairness occurs in the service among the users of the different service classes.
Existence of the unfairness among the users of the same service class and among the users of the different services makes it impossible to provide high-cost performance services. Therefore, there was a drawback that improvement in a degree of satisfaction of users is difficult.